Preparation of CeO2 Polishing Powder and Its Performance and Mechanism for Chemical Mechanical Polishing of Optical Glass

CeO2 polishing powder is extensively used in chemical mechanical polishing (CMP) applications on Si substrate materials. This study synthesized sub-micrometer, spherical, fluoride-free, and fluorine-doped CeO2 particles using the precipitation method at various calcination temperatures. Key parameters of the CeO2 particles, such as particle size, morphology, crystallinity, and Ce3+ content, were obtained using a laser particle size analyzer (LPSA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In conjunction with CMP experiments on K9 optical glass, the service life and polishing performance were evaluated. It was determined that crystallinity is the most critical factor, with a particularly pronounced role of the (111) crystal plane. Fluorine can enhance crystallinity and promote grain growth; hence, fluorine doping can improve the crystallinity of the powder at relatively low calcination temperatures (600 °C), reducing energy consumption. Additionally, appropriate particle size, rough surface morphology, and hydrophilicity of particles can also contribute to the enhancement of material removal rate (MRR). Fourier transform infrared spectroscopy (FT-IR) confirmed that Ce-O-Si bonding during the CMP process facilitated the disintegration of the glass. XPS verified that some Ce4+ can be reduced to Ce3+ during the CMP process, and the presence of Ce3+ can strengthen Ce-O-Si bonding. Ultimately, the glass is primarily removed in a lumped Q3 (Si2O52- sheet) form through the formation of Ce-O-Si bonds at the CeO2-glass interface. This study further refines the polishing mechanism of CeO2 with glass during the CMP process, succinctly summarized in the TOC graphic.